A p-n junction, Fabry-Perot type laser of cavity length L and mirror reflectance R is to be redesigned to double L, but to maintain the same threshold current density. All other junction and material...

A p-n junction, Fabry-Perot type laser of cavity length L and mirror

reflectance R is to be redesigned to double L, but to maintain the same threshold current density. All other junction and material parameters remain the

same.

(a) What is the new mirror reflectance?

(b) What is the new threshold current in terms of the old threshold current

(ie. a ratio)?